Referring now to FIG. 1, a top view is presented of an example of a known configuration for an automated storage system for preparing customer orders comprising:
an automated storage/removal warehouse 7 comprising several sets (two in this example) each formed by an alley 7a, 7a′ feeding, on either side, a storage shelf 7b, 7c, 7b′, 7c′ with several superimposed stacking levels;
a set of conveyors taking the source loads from the warehouse up to the preparing stations and vice versa. In the example of FIG. 1, we can distinguish:                for the forward operation (i.e. from the automated warehouse 7 up to the preparing stations), conveyors referenced 9a and 9a′ (one per alley) as well as 6 and 8; and        for the return operation (i.e. from the preparing stations up to the automated warehouse 7), conveyors referenced 8′, 6′ as well as 9b and 9b′ (one per alley); in this example, the conveyor 6′ and 8′ are superimposed on the conveyors 6 and 8;        
several customer-order preparing stations 10a to 10f, each occupied by an operator 1a to 1f and extending perpendicularly to the conveyors referenced 8 and 8′; and
a managing system (also called a managing unit) that is a computer-based central managing system responsible for managing the entire (automated storage/removal) system 7, the set of conveyors 6, 6′, 8, 8′, 9a, 9a′, 9b and 9b′ and the preparing stations 10a to 10f).
The managing system also manages the list of customer orders associated with each shipping container (target load) and therefore the sequential order of the customer order lines forming this list, as a function of the location of the storage containers (source loads) in the warehouse, the availability of the trolleys and the elevators of the automated warehouse 7 as well as the needs in terms of items and goods of the different shipping containers to be prepared that succeed one and other at the preparing station. The purpose of this is to optimize all the movements and the preparation times for the shipping containers and ensure synchronization between the arrival, at the preparation station, of a shipping container and the corresponding storage containers (containing goods indicated in the customer order list associated with this storage container).
In the example of FIG. 1, each preparing station comprises two conveyor circuits: a first conveyor circuit for the storage containers, formed by two horizontal columns of conveyors; one column (the forward column 2) for shifting these storage containers from the third sub-assembly of conveyors 8 up to the operator 1a and the other (the return column 3) for the reverse shift; and a second circuit of conveyors for the shipping containers, formed by two horizontal columns of conveyors: one (forward column 4) for shifting the shipping containers from the third sub-assembly of conveyors 8 up to the operator 1a and the other (return column 5) for the reverse shift.
A buffer storage function (also called a “accumulation function”) for a determined quantity of containers upstream to the operator (or automaton) is set up in each of the first and second circuits, by the forward column 2 and 4 (consisting of classic horizontal conveyors). A storage container therefore makes the following journey: it is picked up by a trolley in the automated warehouse 7, and is then conveyed successively by one of the conveyors 9a and 9a′ (depending on whether it arrives at the alley 7a or 7a′) and by the conveyors 6 and 8 and finally by the conveyors of the forward column 2 to be presented to the operator. In the other direction (after presentation to the operator), the storage container makes the reverse journey: it is conveyed by the conveyors of the return column 3, then by the conveyors 8′ and 6′ and finally by one of the conveyors 9b and 9b′ (depending on whether it is returning to the alley 7a or 7a′) and is then re-positioned in the automated warehouse 7 by means of a trolley.
As mentioned further above, the containers (source loads and target loads) must be presented to the operator in a desired sequential order forming at least one determined sequence. Classically, this sequential order of arrival is pre-determined by the managing system (i.e. it is determined, for each container, before this container reaches the preparing station) and, if necessary, recomputed during the conveyance of the containers from the exit of the automated warehouse 7 to the preparing station (for example to take account of a malfunctioning of an element of the system).
In a first known (standard) implementation, a first sequencing level is made by the deposition, on each of the conveyors 9a and 9a′, of the pre-sequenced loads (there are therefore constraints on the automated warehouse 7). In other words, the loads deposited on the conveyor 9a are in a sequential order consistent with that of the final desired sequential order and the loads deposited on the conveyor 9a′ are also in a sequential order consistent with that of the final desired sequential order. Then, a second level of sequencing is made through the deposition on the conveyor 6, in the final desired sequential order, of the loads coming from the conveyors 9a and 9a′. For example, for a sequence of seven loads, if the loads of ranks 1, 2, 4 and 5 are stored in the alley 7a, they are deposited in this order on the conveyor 9a and if the loads of the ranks 3 and 6 are stored in the alley 7a′, they are deposited in this order on the conveyor 9a′; then, the seven loads are deposited on the conveyor 6 in ascending order (from 1 to 7) of their ranks.
In a second known implementation, in order to relax the constraints on the automated warehouse 7, it is accepted that the containers will not exit the automated warehouse 7 in the desired sequential order (i.e. the order in which they must be presented to the operator). An operation therefore needs to be carried out for sequencing the containers between the automated warehouse 7 and the preparing station where the operator is situated. The elimination of the sequencing constraints that usually weigh on the automated warehouse 7 significantly increases the performance of this automated warehouse (and generally of the different upstream devices) and therefore enables a reduction of its size and complexity and therefore its cost. In the example of FIG. 1, this sequencing operation is performed as follows: the storage containers circulate in a loop on the conveyors 6, 8, 8′ and 6′ and when the storage containers awaited on the conveyors of the forward column 2 come before this column (in order to complete the sequence of storage containers awaited at the preparing station), this storage container is transferred to the conveyors of the forward column 2, the other storage containers continuing to circulate in the above-mentioned loop (containers 6, 8, 8′ and 6′). This method is performed for each of the storage containers awaited in the sequence (i.e. in the desired sequential order of arrival at the preparing station).
The two known implementations (based on classic horizontal conveyors) mentioned here above for carrying out the buffer (accumulation) storage functions and sequencing functions have several drawbacks.
First of all, they consumer an excessive of amount of m2 for a smaller running surface height (750 mm typically). An example of this excessive footprint is the fact that the surface area needed for six order-preparing stations (as in the example of FIG. 1) is about 100 m2.
Another drawback is that the density on the ground of classic horizontal conveyors (in the preparing stations) is such that it makes it difficult to obtain maintenance access to these conveyors (the conveyor coverage area is too dense).
Another drawback is that, without further increasing the footprint of the preparing station (by increasing the length of the forward column of each of the first and second circuits), it is not possible to increase the number of containers that can accumulate (by buffer storage) upstream to the operator (or automaton).
The invention, in at least one embodiment, is aimed especially at providing a system of buffer storage and sequencing of loads that can overcome the drawbacks of the prior art technique of FIG. 1.